Malicious RTF — malware analysis report

Static analysis result for SHA-256 83ab4f32f5f5eb93…

MALICIOUS

RTF

1.76 MB Created: 2018-12-31 11:10:00 First seen: 2019-12-09
MD5: 4154e09bde7dc3701ba772649f71a333 SHA-1: 205eea8a056fa4ceb79640c34ad9d0c5d8a9da0e SHA-256: 83ab4f32f5f5eb93db0bcf3c999b3e18ecbd6a5bdbaadee700aac9d97a127d62
302 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF document contains embedded OLE objects and exhibits critical heuristic firings for CVE-2017-11882 (Equation Editor FONT record overflow) and CVE-2017-8759 (MSXML SAX OLE activation). These exploits are likely used to download and execute the MSI payload from the unknown reputation URL http://freetalksa.xyz/cryted.msi. The document body appears to be a proforma invoice, a common lure for phishing attacks.

Heuristics 8

  • CVE-2017-11882 — Equation Editor FONT record overflow critical CVE likely CVE_2017_11882
    Equation Editor MTEF contains an overlong FONT typeface field, the vulnerable copy primitive for CVE-2017-11882. This is stronger evidence than the Equation Editor CLSID alone because it identifies the malformed record that drives code execution in EQNEDT32.EXE.
  • CVE-2017-8759 — MSXML SAX OLE activation critical CVE likely CVE_2017_8759
    RTF contains a hex-encoded OLE1 object for Msxml2.SAXXMLReader.6.0 followed by an embedded OLE compound document, and the document requests OLE activation. This matches the RTF staging shape used for CVE-2017-8759 SOAP/WSDL parser code injection.
  • ClamAV: Doc.Exploit.Cve_2017_11882-7570663-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Exploit.Cve_2017_11882-7570663-1
  • \objupdate forces OLE activation high RTF_OBJUPDATE
    RTF contains \objupdate — forces automatic OLE object instantiation when the document is opened, bypassing user interaction. Almost exclusively seen in Equation Editor exploit documents.
  • Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX
    RTF contains ~1576KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    RTF contains 1 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://freetalksa.xyz/cryted.msi In RTF body
    • http://schemas.microsoft.com/office/word/2003/wordmlIn RTF body

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0018d13f.bin rtf-objdata-decoded RTF \objdata at offset 0x18D13F 15672 bytes
SHA-256: 43a0d163fad32c15aaa2d95f2352526f3de5a84204934f958dcbf07d1c2f3b56

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